In transportation vehicles such as automobiles, railroad vehicles, vessels, and aircrafts, noise and vibration are generated due to various kinds of factors.
For example, an engine or a motor that is an automobile power source generates noise and vibration while the engine or the motor is being driven. In addition, while an automobile travels, noise and vibration are generated in the vehicle body by an uneven road surface or the like. If such noise and vibration are directly transmitted into the vehicle body (cabin), occupants in the vehicle may be uncomfortable.
In view of this, techniques for suppressing such noise and vibration have been developed heretofore. For example, Patent Literature 1 discloses a sound attenuating patch for reducing noise and vibration of a panel assembly. For another example, Patent Literature 2 discloses a vehicle floor tub for reducing noise and vibration which are transmitted into the vehicle.
The sound attenuating panel disclosed in Patent Literature 1 is adhered on a main panel of the panel assembly with an adhesive layer. In the vehicle floor tub disclosed in Patent Literature 2, a noise attenuating patch is adhered on a main panel with an adhesive layer. Thus, each of the sound attenuating panel of Patent Literature 1 and the noise attenuating panel of Patent Literature 2 is used by being adhered on the main panel in order to reduce noise and vibration.